cmd/vendor: update github.com/google/pprof

Sync @ fde099a (Oct 26, 2018)

Also update misc/nacl/testzip.proto to include new testdata.
Change-Id: If41590be9f395a591056e89a417b589c4ba71b1a
Reviewed-on: https://go-review.googlesource.com/c/147979
Run-TryBot: Hyang-Ah Hana Kim <hyangah@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

1 files changed, 18 insertions, 10 deletions

diff --git a/src/cmd/vendor/github.com/google/pprof/internal/elfexec/elfexec.go b/src/cmd/vendor/github.com/google/pprof/internal/elfexec/elfexec.go
index 4750ec8129..03083baf12 100644
--- a/src/cmd/vendor/github.com/google/pprof/internal/elfexec/elfexec.go
+++ b/src/cmd/vendor/github.com/google/pprof/internal/elfexec/elfexec.go
@@ -178,8 +178,7 @@ func GetBase(fh *elf.FileHeader, loadSegment *elf.ProgHeader, stextOffset *uint6
 		pageOffsetPpc64 = 0xc000000000000000
 	)
 
-	if start == 0 && offset == 0 &&
-		(limit == ^uint64(0) || limit == 0) {
+	if start == 0 && offset == 0 && (limit == ^uint64(0) || limit == 0) {
 		// Some tools may introduce a fake mapping that spans the entire
 		// address space. Assume that the address has already been
 		// adjusted, so no additional base adjustment is necessary.
@@ -189,9 +188,24 @@ func GetBase(fh *elf.FileHeader, loadSegment *elf.ProgHeader, stextOffset *uint6
 	switch fh.Type {
 	case elf.ET_EXEC:
 		if loadSegment == nil {
-			// Fixed-address executable, no adjustment.
+			// Assume fixed-address executable and so no adjustment.
 			return 0, nil
 		}
+		if stextOffset == nil && start > 0 && start < 0x8000000000000000 {
+			// A regular user-mode executable. Compute the base offset using same
+			// arithmetics as in ET_DYN case below, see the explanation there.
+			// Ideally, the condition would just be "stextOffset == nil" as that
+			// represents the address of _stext symbol in the vmlinux image. Alas,
+			// the caller may skip reading it from the binary (it's expensive to scan
+			// all the symbols) and so it may be nil even for the kernel executable.
+			// So additionally check that the start is within the user-mode half of
+			// the 64-bit address space.
+			return start - offset + loadSegment.Off - loadSegment.Vaddr, nil
+		}
+		// Various kernel heuristics and cases follow.
+		if loadSegment.Vaddr == start-offset {
+			return offset, nil
+		}
 		if start == 0 && limit != 0 {
 			// ChromeOS remaps its kernel to 0. Nothing else should come
 			// down this path. Empirical values:
@@ -202,12 +216,6 @@ func GetBase(fh *elf.FileHeader, loadSegment *elf.ProgHeader, stextOffset *uint6
 			}
 			return -loadSegment.Vaddr, nil
 		}
-		if loadSegment.Vaddr-loadSegment.Off == start-offset {
-			return offset, nil
-		}
-		if loadSegment.Vaddr == start-offset {
-			return offset, nil
-		}
 		if start >= loadSegment.Vaddr && limit > start && (offset == 0 || offset == pageOffsetPpc64 || offset == start) {
 			// Some kernels look like:
 			//       VADDR=0xffffffff80200000
@@ -230,7 +238,7 @@ func GetBase(fh *elf.FileHeader, loadSegment *elf.ProgHeader, stextOffset *uint6
 			//       start=0x198 limit=0x2f9fffff offset=0
 			//       VADDR=0xffffffff81000000
 			// stextOffset=0xffffffff81000198
-			return -(*stextOffset - start), nil
+			return start - *stextOffset, nil
 		}
 
 		return 0, fmt.Errorf("Don't know how to handle EXEC segment: %v start=0x%x limit=0x%x offset=0x%x", *loadSegment, start, limit, offset)